In wildlife forensic science cases, species identification is often essential to the successful prosecution of an offender. Currently, species identification is best achieved through immunological methods; however, these are limited by the cross-reactivity of antisera among different species. To develop a species-specific and highly sensitive technique, the authors used individual DNA size classes as hybridization probes. A discrete DNA size class was isolated from antelope (1.3 kb), elk (1.0 kb), and mule deer (0.8 kb) for use as a radioactive molecular hybridization probe. Genomic DNA in each agarose plug was radioactively labeled and then incubated with a Southern transfer membrane that contained DNA's from 10 species. The hybridization pattern for each probe was unique and easily distinguished among deer, elk, and antelope, but not between the various species of deer. Because of the high number of sequence copies per genome, these probes are extremely sensitive, requiring less than 10 ng of total genomic DNA. 3 figures and 13 references (Author abstract modified)